package com.zhangwei.flashlib.flashview.effect;

import android.support.v4.view.ViewPager.PageTransformer;
import android.view.View;

public class DepthPageTransformer implements PageTransformer {
	private static float MIN_SCALE = 0.5f;

	/**
	 * position����ָ����ҳ���������Ļ���ĵ�λ�á�����һ����̬���ԣ�������ҳ��Ĺ�����ı䡣��һ��ҳ����������Ļ�ǣ����ֵ��0��
	 * ��һ��ҳ��ո��뿪��Ļ���ұ�ʱ
	 * �����ֵ��1��������Ҳҳ��ֱ������һ��ʱ������һ��ҳ���λ����-0.5����һ��ҳ���λ����0.5��������Ļ��ҳ���λ��
	 * ��ͨ��ʹ������setAlpha()��setTranslationX()����setScaleY()����������ҳ������ԣ��������Զ���Ļ���������
	 */
	@Override
	public void transformPage(View view, float position) {
		int pageWidth = view.getWidth();
		if (position < -1) { // [-Infinity,-1)
								// This page is way off-screen to the left.
			view.setAlpha(0);
			view.setTranslationX(0);
		} else if (position <= 0) { // [-1,0]
									// Use the default slide transition when
									// moving to the left page
			view.setAlpha(1);
			view.setTranslationX(0);
			view.setScaleX(1);
			view.setScaleY(1);
		} else if (position <= 1) { // (0,1]
									// Fade the page out.
			view.setAlpha(1 - position);
			// Counteract the default slide transition
			view.setTranslationX(pageWidth * -position);
			// Scale the page down (between MIN_SCALE and 1)
			float scaleFactor = MIN_SCALE + (1 - MIN_SCALE)
					* (1 - Math.abs(position));
			view.setScaleX(scaleFactor);
			view.setScaleY(scaleFactor);
		} else { // (1,+Infinity]
					// This page is way off-screen to the right.
			view.setAlpha(0);
			view.setScaleX(1);
			view.setScaleY(1);
		}
	}

}